This invention relates generally to turbine components, and more particularly to turbine airfoils for use in variable-temperature environments.
A typical gas turbine engine includes a turbomachinery core having a high pressure compressor, a combustor, and a pressure turbine in serial flow relationship. The core is operable in a known manner to generate a primary gas flow. Depending on the particular application, the engine may also include other components such as a fan or booster for generating propulsive thrust, or a power turbine for driving a shaft or a propeller.
The compressor and turbine both include one or more rotor stages each including a plurality of airfoil-shaped blades as well as stationary airfoils. These airfoils are typically of homogenous construction. For example they may be forged from a billet of metal alloy or cast from molten metal alloy.
One problem with existing turbine engine airfoils is that they have a static external surface shape or “fixed geometry” which is most efficient or effective only at one particular gas flow condition or “design point”. While variable-geometry airfoils are known, they typically are mechanically complex and require intervention by an operator or automated control system.
Another problem with fixed geometry turbine engine airfoils is that they are subject to aerodynamic, mechanical, and thermal stresses during operation, which may cause them to deflect from their static shape, deviating from their intended efficiency or effectiveness.